Hi.
If the AP will not be able to reach the new controller - you will not see it UP.
一、Aruba ADP
Once the AP receives the IP address of the master controller, the AP uses this address as the IP address of a TFTP server and downloads its software image. After the AP completes the download of its image, it repeats the boot-up process to obtain the same IP address of the master controller for bootstrapping/obtaining its configuration.
The ADP protocol is the first method that all Aruba APs will use to discover the master. The ADP protocol works as follows:
1 AP sends out a discovery packet
2 Master responds with its own loopback address – local controllers .may also respond with the loopback address of the master
3 AP connects to the correct controller and downloads its configuration as well as any new firmware
4 AP reboots and goes operational with correct configuration
1 Auto Discovery Protocol (ADP) – broadcast
In the broadcast version of ADP, an Aruba AP sends out broadcast packets using the broadcast address 255.255.255.255. The master or local controllers will then respond to the AP with the master loopback address.
Comment:
Important: This method requires the master or other controllers to be located on the same Layer 2 network as the AP.
CLI：
(Aruba2400) (config) #adp discovery enable
(Aruba2400) (config) #adp igmp-join disable
2 Auto Discovery Protocol (ADP) - multicast
With the multicast version, an Aruba AP sends out IP multicast packets using the group address 224.0.82.11. The controllers will reply to the AP with its own loopback IP address.
Comment:
This method requires the network to correctly pass multicast traffic between the AP and the controllers.
CLI:
(Aruba2400) (config) #adp discovery enable
(Aruba2400) (config) #adp igmp-join enable
3 Dynamic Host Configuration Protocol (DHCP Option 43)
DHCP servers are a popular way of configuring clients with basic networking information such as an IP address, a default gateway,
network mask, DNS server, etc. Most DHCP servers have the ability to also send a variety of optional information as well. One of these is the Vendor-Specific Option Code, often called option 43.
Here is how option 43 works:
1 The DHCP client on an Aruba AP adds an optional piece of information called the Vendor Class Identifier Code (Option 60) to
its DHCP request. The value of this code is ArubaAP
2 The DHCP server sees the vendor information and checks if it has option 43 configured, if it does, it will send the Vendor-Specific
Option Code (43) to the client. The value of this option is the loopback address of the Aruba master
3 The AP gets a response from the DHCP server and checks if option 43 was returned, if it was, the AP contacts the master using the
supplied IP address
4 Domain Name Services – DNS lookup
In most cases this is the most popular discovery method. It has the advantage of working very well across both Layer 2 and Layer 3
networks. If an Aruba AP fails to receive the IP address of the master controller via DHCP or either ADP method, the AP will use the IP
address of the domain name server it received from DHCP to perform a DNS lookup.
Comment:
This method requires a DNS host entry that corresponds to the name of the master. By default, APs look for the entry aruba-master.
二、AP Boot Sequence
Aruba AP Dynamic boot sequence
1 AP learns AP Name / AP Group from bootrom
2 AP sends out DHCP request for IP address
3 If DHCP response includes vendor option 43 (masterip), AP will use this for Master IP address
4 If no vendor option specified, AP sends “ADP” packet to Multicast group 239.0.82.11
5 If no response to Multicast ADP, AP sends “ADP” packet as L2/L3 broadcast (configure Master Aruba controller as a DHCP helper recipient)
6 If no response, AP sends DNS query to server given by DHCP for “aruba-master.domain.com” where “domain.com” is domain given by DHCP. AP will use this for Master IP address
Once AP determines Master IP address, boot continues from Step 2 in Static config
AP Static boot sequence
1 AP loads variables from bootrom
2 AP sends message to Aruba controller with its AP Name / AP Group
3 If needed, AP sends an TFTP request to Aruba controller and downloads OS image (establish PAPI (UDP 8211 )连接到无线交换机) (control Protocol)
4 Based on the AP Name / AP Group, the current controller may take control of this AP or direct it to another controller
5 AP authenticates to controller and establishes GRE tunnel
client 与 AP 通信，AP将数据通过 GRE tunnel 传送到无线控制器
三、configuration
adp discovery {disable|enable} igmp-join {disable|enable} igmp-vlan <vlan>
(host) #show adp config
ADP Configuration
-----------------
key value
--- -----
discovery enable
igmp-join enable
igmp-vlan 0
Some Aruba AP boot\pre-boot command syntax examples:
Pre-boot Commands:
apboot> help
? - alias for 'help'
boot - boot the OS image
clear - clear the OS image or other information
date - get/set/reset date & time
dhcp - invoke DHCP client to obtain IP/boot params
factory_reset - reset to factory defaults
help - print online help
mfginfo - show manufacturing info
ping - send ICMP ECHO_REQUEST to network host
printenv - print environment variables
purgeenv - restore default environment variables
reset - Perform RESET of the CPU
saveenv - save environment variables to persistent storage
setenv - set environment variables
tftpboot - boot image via network using TFTP protocol
upgrade - upgrade the APBoot or OS image
version - display version
Environment Variables:
bootdelay=2
baudrate=9600
autoload=n
boardname=Talisker
servername=aruba-master
bootcmd=boot ap
autostart=yes
bootfile=mips32.ari
ethaddr=d8:c7:c8:XX:XX:XX
os_partition=0
ethact=eth0
gatewayip=192.168.1.1
netmask=255.255.255.0
dnsip=8.8.8.8
name=IAP105
domainname=arubanetworks.com
ipaddr=192.168.1.101
stdin=serial
stdout=serial
stderr=serial
Hope it will give u some idea.
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